The sidewalk in front of my house is a low point for the surrounding area and collects about 3" of water when it rains or snows. This means that, unless promptly cleared, the sidewalk is covered in a 10-foot by 3"-thick layer of ice for most of the winter. (I try my best to clear it but am not able to keep up with it all the time.) The ice is too thick to remove by shoveling, and even if I add salt the water has nowhere to go.
A. Water/Dirt from property running onto sidewalk